I collect all Topps and Bowman sets, so I needed Mantle cards to complete sets. Since I like to collect hobby recognized variations with my sets, this unfortunately required 2 of the 52 Mantles.
I have some gold (not coins) as a diversification investment, but cards are just a hobby for me, albeit in some cases an expensive one.
I personally get a kick out of the debate about the value of the 52 Mantle card and how much some folks get so worked up about the rookie card thing. I do agree that it usually seems people who disparage the 52 Mantle card don't have it
Also agree that some of the Topps Mantle cards( not the 52) are among the rarest in the hobby, much more so than the T 206 Wagner. But they are from obscure sets with little recognition or following.